Installation for manufacturing metal strips and method of operating same

ABSTRACT

The invention essentially is characterized in that downstream of the casting machine and upstream of the rolling device, in particular immediately behind shears for cutting the thin slab or the pre-strip, there is provided a scrap removal device, in particular a coiling device that winds the thin slabs or pre-strip into a coil which is removed from the installation as scrap. Therefore, the quality of the coil winding is not important as the wound then slab or pre-strip need not anymore be advanced to the rolling train. The resulting coil can be lifted with a forklift and bind during the emergency maintenance of the rolling train, without use of any personnel. No additional crane is required for scrap removal. In addition, no constructional measures, e.g., construction of a gravel pit for material cut by shears, are necessary.

The invention relates to an installation for manufacturing metal strips, in particular to a casting and rolling installation, and having at least one casting machine for casting thin slabs or a prestrip; at least one rolling device located downstream of the casting machine and having several rolling stands for rolling the thin slabs in metal strips of a predetermined thickness, and at least one furnace provided upstream of the system of rolling stands.

The invention further relates to a method of operating an installation for manufacturing metal strips, in particular of a casting and rolling installation, and having at least one casting machine for casting thin slabs or a prestrip; at least one rolling device located downstream of the casting machine and having a system of rolling stands for rolling the thin slabs in metal strips of a predetermined thickness, and at least one furnace.

Metal strips, in particular, steel strips having a thickness from 0.8 mm to 3 mm are produced from cast thin slabs or pre-strip having a thickness about between 40 and 140 mm in batch operation, semi-continuous operation, and continuous operation. In a casting and rolling installation, liquid steel is cast into thin slabs or a pre-strip which after temperature equalization, e.g., in a tunnel furnace, is directly rolled in a thin strip in a rolling train. The casting and rolling installations are characterized, in particular, by a directed connection of casting and rolling. This means that the casting process and the rolling process follow each other after the heating process.

Downtime of rolling trains, e.g., as a result of a non-planned roll exchange is not a rarity. In this case, it is desirable and it makes sense not to interrupt the casting process. To this end, different types of shears for chopping steel sheets can be provided in the rolling train and also in a tunnel furnace. Thus, e.g., emergency shears are used for disconnecting the casting machine from the rolling train. The chopped-off scrap material is transmitted to a container and need be disposed. To this end gravel pits should be provided and for providing of which, expensive groundwork is required. Finally, the shears in front of a finishing train are relatively slow. The removed scrap falls in a container and need be disposed. This requires workers and use of a crane for scrap removal.

An installation of the above-mentioned prior art is disclosed in WO2009/036894. In this casting and rolling installation, a storage coiler is integrated in a roller table for batch operation and semi-continuous operation. The coiler stores a pre-strip coming from a roughing stand, with the coiler being deactivated in case of a continuous operation. The installation described in WO2009/036894, has a group of roughing stands and a group of finishing stands. If the storage is in front of the group of finishing stands, the storage coiler in form of a jumbo coilbox can be used for storage of the pre-strip, with the pre-strip being rolled in the group of roughing stands and finally, wound in the storage coiler. Upon renewal of operating of the group of finishing stands, the coil, which is intermediately stored in the storage coiler, is unwound, forwarded in the finishing train, and is finish-rolled. In order to be able to forward the wound strip into the process, it is necessary that the strip be cleaned before being wound. Therefore, the strip beginning or the strip end should be correspondingly prepared.

Accordingly, the object of the invention is to improve the state-of-the art installation so that decoupling of the casting machine from the rolling device in case of emergency can be achieved with relatively simple means. A further object of the invention is a corresponding method of operating such an installation.

The objects of the invention are achieved with features of claims 1 and 6. Advantageous improvements of the invention follow from dependent claims.

The invention essentially is characterized in that downstream of the casting machine and upstream of the rolling device, in particular immediately behind shears for cutting the thin slab or the pre-strip, there is provided a scrap removal device, in particular a coiling device that wounds the thin slabs or pre-strip into a coil which is removed from the installation as scrap. Therefore, the quality of the coil wounding is not important as the wound then slab or pre-strip need not anymore be advanced to the rolling train. The resulting coil can be lifted with forklift and bind during the emergency maintenance of the rolling train, without use of any personnel. No additional crane is required for scrap removal. In addition, no constructional measures, e.g., construction of a gravel pit for material cut by shears, are necessary.

The coiling device of the inventive installation can be relatively simple as the quality of the coil winding is not important because the coil is to be removed from the process as scrap. The inner diameter of the wound coil is likewise not important (does not play any role).

According to the advantageous embodiment of the inventive installation, the scrap removal device is provided immediately upstream of the first furnace.

Additionally, there is provided a second or further furnace, e.g., downstream of provided roughing stands of the installation.

In an alternative embodiment of the inventive installation, the scrap removal device is located immediately downstream of the first furnace or the second furnace that, preferably, is formed as a tunnel furnace.

The tunnel furnace is preferably so formed that it can store a certain number of thin slabs or a quantity of the pre-strip and, thus, acts as a buffer between the casting machine and the rolling device or a portion of the rolling device.

The scrap removal device according to the invention which is formed as a coiling device, provides an additional buffer for a non-planned roll exchange in the rolling train.

By operation of the inventive scrap removal device, e.g., decoupling of at least one or several casting machine from the rolling device, it can be achieved that the tunnel furnace can be emptied in order to prevent interruption of the casting operation.

A particular advantageous embodiment of the installation according to the present invention is formed as a casting and rolling installation without roughing stands.

The object of the present invention is further achieved by a method of operating an installation for manufacturing metal strips, in particular, a casting and rolling installation, comprising at least one casting machine for casting thin slabs or pre-strip, at least one rolling device located downstream of the casting machine and having a system of rolling stands, for rolling the thin slabs or pre-strip in metal strips of a predetermined thickness, and at least one first furnace. The method is characterized in that during downtime of the rolling device, the thin slabs or pre-strip which leaves the casting machine are removed, between the casting machine and the rolling device, from the installation as scrap being wound into a coil by a scrap removal device formed as a coiling device.

The installation can operate selectively in continuous operation, semi-continuous operation and in a batch operation.

Advantageously, during the still stand of the rolling device, the casting speed of the strand-producing casting machine is reduced.

For an alternative embodiment of inventive installation, the method contemplates that at downtime of the rolling device, the thin slabs or the pre-strip are/is removed from the installation until the tunnel furnace that acts as a buffer, becomes empty. For emptying the tunnel furnace, e.g., downstream of the tunnel furnace, a storage coiler or coil box for winding and receiving the pre-strip can be provided, which pre-strip can be introduced in the process after the downtime of the installation ends.

The invention will further be described on the basis of several embodiments with reference to the accompanying drawings.

The drawings show:

FIG. 1 a schematic view of a first embodiment of the installation according to the present invention,

FIG. 2 a schematic view of a second embodiment of the installation according to the present invention, and

FIG. 3 a schematic view of a third embodiment of the installation according to the present invention.

FIG. 1 shows a casting and rolling installation having a casting machine 1 with a casting machine outlet 2 and a located downstream, rolling installation or rolling train. Downstream of the casting machine outlet 2, first shears 3 are located for cutting a strand 4 that leaves the casting machine outlet 2, into separate thin slabs or pre-strips. Downstream of the shears 3, a first furnace 5 is located that, e.g., can be formed as an induction furnace. The term “downstream” means, on one hand, in the flow direction of the strand 4 of the cast steel, and on the other hand, in the transportation direction of the thin slab in and/or pre-strip cut by the shears 3, and/or in the transportation direction of a rolled metal strip. Between the first shears 3 and the first furnace 5, according to the invention, there is provided a scrap disposal device in form of a coiling device 9.

Downstream of the first furnace 5, there are provided two rolling stands 10, and downstream of the two rolling stands 10, there is provided a second furnace 6 formed, e.g., as a tunnel furnace. Thereafter, there are provided the second shears 7 and several finishing stands 8. Other parts of the installation, e.g., a reel for winding the finished rolled strip, are not shown for simplification purposes.

In the installation shown in FIG. 1, there are provided both the roughing stands 10 and the finishing stands 8. The second furnace 6 is a tunnel furnace serves for an inductive heating and storing of the pre-strip. In case of downtime of the finishing stands 8, the cut-off, by the first shears 3, thin slabs or the pre-strip are coiled by the coiling device 9 and are removed from the process, e.g., by a fork lift, while the second furnace 6 is being emptied. The pre-strip which is stored in the second furnace 6, can be wound on coil storage device or coil box, not shown, and later again be fed into the process.

In the installation shown in FIG. 2, no roughing stands are contemplated. In FIG. 2, the same components are designated with the same reference numerals. The installation includes a casting machine 1 and an adjoining rolling train with several rolling stands 8. In the flow direction, behind the casting machine outlet 2, there are provided first shears 3 and first furnace 5 which, in the case of the second embodiment, is formed as a tunnel furnace according to FIG. 2. Immediately, behind the first furnace 5, there is provided the coiling device 9 according to the present invention.

A flame cutter 11 is provided in both the first embodiment and in the second embodiment. In the installation shown in FIG. 1, the flame cutter 11 is arranged behind the roughing stands 10, in the installation shown in FIG. 2, the flame cutter is arranged behind the coiling device 9.

The embodiment shown in FIG. 3 corresponds substantially to the embodiment of FIG. 1. In the embodiment according to FIG. 3 the roughing stands 10 are arranged behind the first furnace 5. Behind the roughing stands 10, there is provided the second furnace 6. The inventive coiling device 9 is located immediately behind the second furnace 6 and in front of second shears 7. In this embodiment, an additional coiler for storing a prestrip is provided.

LIST OF REFERENCE NUMERALS

-   1 Casting machine -   2 Casting machine outlet -   3 First shears -   4 Strand -   5 First furnace -   6 Second furnace -   7 Second shears -   8 Finishing stands -   9 Coiling device -   10 Roughing stands 

1-5. (canceled)
 6. A method of operating an installation for manufacturing metal strips, comprising at least one casting machine (1) for casting thin slabs or pre-strip, at least one rolling device located downstream of the at least one casting machine (1) and having a system of rolling stands, for rolling the thin slabs or, the pre-strip in metal strips of a predetermined thickness, and at least one first furnace (5), characterized in that during downtime of the at least one rolling device, the thin slabs or the pre-strip which leaves the at least one casting machine (1) are removed, between the at least one casting machine (1) and the at least one rolling device, from the installation by being wound into a coil by at least one scrap removal device formed as coiling device (9), with the coil to be disposed with as scrap.
 7. A method according to claim 6, characterized in that during the downtime of the at least one rolling device, a casting speed of a strand (4) of the at least one casting machine (1) is reduced.
 8. A method according to claim 6, characterized in that during the downtime of the at least one rolling device, the thin slab or the pre-strip is removed from the installation until a tunnel furnace that acts as a temporary storage becomes empty. 